The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Nov. 03, 1992
Filed:
Mar. 07, 1991
Harumasa Kajita, Fujisawa, JP;
Toyokazu Yanagimichi, Chigasaki, JP;
Tetsuo Kariya, Fujisawa, JP;
Toshikazu Wakabayashi, Fujisawa, JP;
Ichiro Kawashima, Chigasaki, JP;
Satoshi Nakanami, Kamakura, JP;
Masami Tanaka, Yokohama, JP;
Matsushita Electric Industrial Co., Ltd., Osaka, JP;
Abstract
A cable television system includes a transmitter and at least one receiver. In the transmitter, sync information is suppressed in amplitude to execute scrambling, and a sync width information signal and key data are superimposed on a television signal during a vertical blanking period. The sync width information signal has a burst form and a predetermined width, and represents whether sync information is present or absent. The key data represents contents of the scrambling. In the receiver, the sync width information signal is recovered, and a sync width information pulse corresponding to the sync width information signal is generated. A reference signal is generated on the basis of an edge of the sync width information pulse. The key data is extracted from the scrambled video information in response to the reference signal. Pseudo sync signals are generated in response to an edge of the sync width information pulse. The sync information of the scrambled video information is increased in amplitude in response to the extracted key data at timings determined by the pseudo sync signals.